1. Field of the Invention
This invention relates to a method and an apparatus for cutting a continuously-fed flat tube into cut tubes each having a given length.
2. Description of the Prior Art
U.S. Pat. No. 5,133,492 discloses a method of separating a thin-walled multiport extrusion into a plurality of micro-tubes usable in a heat exchanger assembly. In the method disclosed by U.S. Pat. No. 5,133,492, grooves corresponding to cutting lines are provided in the upper and lower walls of the extrusion, and portions of the extrusion on opposite sides of the grooves are drawn in opposite directions to tear the extrusion apart along the cutting lines. Thus, the method disclosed by U.S. Pat. No. 5,133,492 has two steps, that is, a step of providing the grooves (the cutting lines) and a step of tearing the extrusion apart along the cutting lines.
Japanese published examined patent application 3-56808 discloses a method of cutting a flat tube into cut tubes usable in a heat exchanger assembly. In the method disclosed by Japanese application 3-56808, grooves are provided in the upper and lower walls of the flat tube by moving a disk cutter across the flat tube, and an end portion of the flat tube on one side of the grooves is swung about the grooves to separate the end portion from the remaining portion of the flat tube. Thus, the method disclosed by the Japanese application 3-56808 has two steps, that is, a step of providing the grooves and a step of dividing the flat tube into two along the grooves.
Japanese published examined patent application 4-78407 discloses a cutting apparatus in which a female blade constitutes a fixed blade. The female blade has an opening through which a work piece is inserted. A male blade is linearly moved along the opening to cut the work piece. In the cutting apparatus of Japanese application 4-78407, the male blade is slid on the fixed female blade during the cutting process. Since this design tends to cause a certain level of a force of deforming the work piece, the cutting apparatus of Japanese application 4-78407 seems to be unsuited for cutting a flat tube having multiple ports.